Small, cationic antimicrobial peptides (AMPs) are naturally occurring antibiotics of the innate immune system. AMPs are widely distributed in animals and plants and are among the most ancient host defense factors (Hofmann et al., 1999). Their spectrum of activity includes Gram-positive and Gram-negative bacteria as well as fungi and certain viruses. As resistance of pathogenic microbes to conventional antibiotics increases, researchers are exploring these endogenous antibiotics as a potential source or new therapies against variety of infectious diseases.